Various power conversion architectures have been developed and used in a wide range of applications. Two common power conversion architectures are half bridge architectures and full bridge architectures.
In half bridge architectures using symmetrical drive, a disadvantage is that, at anything less than a maximum drive duty factor, there are “dead times” during which switches in the half bridge are not active (conducting). This can cause currents to flow through the body diodes of the switches, resulting in significant losses (often on an order of equal to or greater than I2R losses). Placing Schottky diodes in parallel with the switches can help but can still result in significant Schottky losses during some operating conditions. While asymmetrical drive can solve the dead time problem, a disadvantage is that it typically results in poor waveform quality, which can require much lower impedance in a matching network. This increases half bridge circulating RMS current, which again increases losses.
Full bridge architectures with phase modulation can solve the dead time problem since current always flows though two actuated switches. However, full bridge architectures force a load to be driven differentially at a high common mode voltage, which can be a significant drawback in certain applications.